Jazzycat you should add some version of the dump truck with a tri-axle set up as they are more common in the USA then a tandem axle set up
refering to the rear axles, excluding the steering axle
the first of the rear three axles is a lift axle
then the uncommon quad-axle set up
5 axles
6 axles seems to be the most, cant say ive ever seen more without getting in to trailers
tri-axle is also popular with cement trucks
and fuel tanker trucks and garbage trucks, however on a garbage truck the lift axle is the rear most axle in the set of three usually